Lesions will be made in cortical visual areas of the cat (areas 17,18, 19, and the lateral suprasylvian area). Fiberdegeneration will be studied in the pontine nuclei using Nauta and Fink-Heimer stains. Horseradish peroxidase (HRP) will be injected into the pontine visual area. Retrograde transport and staining of this enzyme should allow us to determine relative importance of each of the cortical areas as well as which cortical cell types project to the pons. Pontine visual cells will be activated by electrical stimulation of visual cortex to see from which areas pontine cells can be monosynaptically activated and the latency of such activation. Visual areas of the cerebral cortex will be cooled or destroyed to determine effects on pontine visual cell response properties. Exploratory experiments will be carried out to see if caudate nucleus cells in the region of caudate to which visual cortex projects can be visually activated.